Regenerative medicine can be defined as harnessing the body's regenerative mechanisms in a clinically targeted manner, using them in ways that are not part of the normal healing mechanism or by artificially amplifying normal mechanisms. Stem cells are pluripotent or multipotent cells with the potential to differentiate into a variety of other cell types, which perform one or more specific functions and have the ability to self-renew. It has been found that stem cells from a variety of sources can be used for multiple therapeutic or prophylactic purposes. For example, hematopoetic stem cells (HSCs) derived from bone marrow are multipotent stem cells that can give rise to cell types from the myeloid (monocytes and macrophages, neutrophils, basophils, eosinophils, erythrocytes, megakaryocytes/platelets, dendritic cells), and lymphoid lineages (T-cells, B-cells, NK-cells). Mesenchymal stem cells (“MSCs”) derived from multiple tissues in the adult body are multipotent non-hematopoietic stem cells and are characterized by extensive proliferative ability in an uncommitted state while retaining the potential to give rise to cell types including osteoblasts, myocytes, chondrocytes, adipocytes, endothelial cells and beta pancreatic islet cells. MSCs are present in which arise from the embryonic mesoderm (e.g., hematopoietic cells and connective tissue). Thus, stem cells can be isolated from many tissue sources within the adult body.
Adipose tissue refers to fat including the connective tissue that stores the fat. Adipose tissue includes stem cells and endothelial precursor cells. As used herein, “adipose tissue” refers to a tissue containing multiple cell types including adipocytes and microvascular cells. It has been discovered that adipose tissue is an especially rich and practical source of mesenchymal stem cells. This finding is due, at least in part, to the ease of harvesting adipose tissue and the ease of removing the major non-stem cell component of adipose tissue, the adipocyte. In fact, a large quantity of mesenchymal stem cells can be obtained by simple aspiration from adipose tissue, for example, from lipoaspirate samples from aesthetic interventions. The lipoaspirate is typically centrifuged to separate the active cellular component from the mature adipocytes and connective tissue. The pellet containing the active cellular component (e.g., the component containing adipose-derived stem cells) is referred to as processed lipoaspirate (PLA).
Adipose-derived stem cells (ADSCs), methods for extracting such cells and methods for using such cells are disclosed for example in: Gimble et al., “Adipose-derived Stem Cells for Regenerative Medicine” Circ. Res. 100:1249-1260 (2007); Utsonomiya et al., “Human Adipose-Derived Stem Cells: Potential Clinical Applications in Surgery” Surg Today 41:18-23 (2011); Casteilla et al., “Adipose-derived stromal cells: Their identity and uses in clinical trials, an update” World J Stem Cells 3(4):25-33 (2011); U.S. Pat. No. 6,777,231 entitled “Adipose-Derived Stem Cells and Lattices” to Katz et al.; U.S. Pat. No. 7,901,672 entitled “Methods Of Making Enhanced Autologous Fat Grafts” to Fraser et al.; U.S. Patent Publication 2009/0304644 entitled “Systems And Methods For Manipulation Of Regenerative Cells Separated And Concentrated From Adipose Tissue” to Hedrick et al.; and U.S. Pat. No. 7,390,484 entitled “Self-Contained Adipose Derived Stem Cell Processing Unit” to Fraser et al., all of which are incorporated herein by reference.